Vehicular antenna, vehicular antenna-attached window glass, and antenna system

ABSTRACT

A vehicle antenna includes a conductor plate, a radiator plate facing the conductor plate, a feeding portion located on a same side as the conductor plate with respect to the radiator plate, a connection conductor connecting the feeding portion and the radiator plate, and a first element and a second element arranged away from each other on both sides in a vehicle-width direction of a vehicle with respect to the radiator plate, wherein the radiator plate is arranged at an inclination of equal to or less than ±15 degrees with respect to a vertical plane perpendicular to a horizontal plane.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Continuation of U.S. patent applicationSer. No. 17/073,917, filed on Oct. 19, 2020, which is a BypassContinuation of International Patent Application No. PCT/JP2019/016900,filed on Apr. 19, 2019, which claims priority to Japanese PatentApplication No. 2018-083263 filed on Apr. 24, 2018. The entire contentsof the foregoing applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a vehicle antenna, a vehicleantenna-attached window glass, and an antenna system.

2. Description of the Related Art

In recent years, there is an ongoing trend of, for example, a transitionfrom 4G LTE to 5G (sub6) to expand services using high-speed andlarge-capacity wireless communication systems communicating in microwaveand millimeter wave frequency bands. For example, for V2X (Vehicle toEverything) communication such as vehicle-to-vehicle communication androad-to-vehicle communication, an antenna device that supplies power totwo or more dipole antennas provided on a substrate via parallel 2-wiretransmission lines provided on the substrate is known as an antenna usedfor such communication (for example, see PTL 1).

CITATION LIST Patent Literature

-   PTL 1: International Publication No. 2017/213243

SUMMARY OF THE INVENTION Technical Problem

However, with conventional vehicle antennas, it used to be difficult toobtain a sufficient antenna gain in a desired direction.

Therefore, the present disclosure provides a vehicle antenna with animproved antenna gain in a desired direction, and provides vehicleantenna-attached window glass including at least one such vehicleantenna, and an antenna system.

Solution to Problem

The present disclosure provides a vehicle antenna including:

a conductor plate;

a radiator plate facing the conductor plate;

a feeding portion located on a same side as the conductor plate withrespect to the radiator plate;

a connection conductor connecting the feeding portion and the radiatorplate; and

a first element and a second element arranged away from each other onboth sides in a vehicle-width direction of a vehicle with respect to theradiator plate,

wherein the radiator plate is arranged at an inclination of equal to orless than ±15 degrees with respect to a vertical plane perpendicular toa horizontal plane.

Also, the present disclosure provides a vehicle antenna including:

a conductor plate;

a radiator plate facing the conductor plate;

a feeding portion located on a same side as the conductor plate withrespect to the radiator plate;

a connection conductor connecting the feeding portion and the radiatorplate; and

a single element arranged away from the conductor plate and the radiatorplate, and located away from a center of gravity of the radiator plate,as viewed from a same side as the radiator plate with respect to theconductor plate,

wherein the radiator plate is arranged with an inclination of equal toor less than ±15 degrees with respect to a vertical plane perpendicularto a horizontal plane.

Also, the present disclosure provides a vehicle antenna-attached windowglass including at least one such vehicle antenna and an antenna system.

Advantageous Effects of Invention

According to the present disclosure, the antenna gain in the desireddirection is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an example of vehicleantenna-attached window glass.

FIG. 2 is a partially enlarged view illustrating, in a front view, anexample of vehicle antenna-attached window glass.

FIG. 3 is a partially enlarged view illustrating, in a side view, anexample of vehicle antenna-attached window glass.

FIG. 4 is a perspective view illustrating an example of a portion of aconfiguration of a vehicle antenna.

FIG. 5 is a cross sectional view illustrating an example of a portion ofa configuration of a vehicle antenna.

FIG. 6 is a drawing illustrating an example of an antenna system havingmultiple vehicle antennas.

FIG. 7 is a diagram illustrating an example of a measurement result ofdirectivity of a vehicle antenna.

FIG. 8 is a drawing illustrating a first configuration example of avehicle antenna.

FIG. 9 is a drawing illustrating a second configuration example of avehicle antenna.

FIG. 10 is a drawing illustrating a third configuration example of avehicle antenna.

FIG. 11 is a diagram illustrating an example of a measurement result ofdirectivities of vehicle antennas.

FIG. 12 is a drawing illustrating an example of a measurement result ofantenna gains in a vehicle-width direction.

FIG. 13 is a drawing illustrating a fourth configuration example of avehicle antenna.

FIG. 14 is a diagram illustrating an example of a measurement result ofdirectivities of vehicle antennas.

FIG. 15 is a drawing illustrating an example of a measurement result ofantenna gains in the vehicle-width direction.

FIG. 16 is a drawing illustrating a fifth configuration example of avehicle antenna.

FIG. 17 is a diagram illustrating an example of a measurement result ofdirectivities of vehicle antennas.

FIG. 18 is a drawing illustrating a sixth configuration example of avehicle antenna.

FIG. 19 is a drawing illustrating a seventh configuration example of avehicle antenna.

FIG. 20 is a diagram illustrating an example of a measurement result ofdirectivities of vehicle antennas.

FIG. 21 is a drawing illustrating an example of a measurement result ofantenna gains in the vehicle-width direction.

FIG. 22 is a drawing illustrating an eighth configuration example of avehicle antenna.

FIG. 23 is a diagram illustrating an example of a measurement result ofdirectivities of vehicle antennas.

FIG. 24 is a drawing illustrating a ninth configuration example of avehicle antenna.

FIG. 25 is a diagram illustrating an example of a measurement result ofdirectivities of vehicle antennas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment according to the present disclosure isdescribed with reference to drawings. In each embodiment, deviationsfrom directions such as parallel direction, perpendicular direction,orthogonal direction, horizontal direction, vertical direction, heightdirection, width direction, and the like are tolerated so long as theeffects of the present invention are not impaired. Further, an X axisdirection, a Y axis direction, and a Z axis direction represent adirection parallel to the X axis, a direction parallel to the Y axis,and a direction parallel to the Z axis, respectively. The X axisdirection, the Y axis direction, and the Z axis direction are orthogonalto each other. The XY plane, the YZ plane, and the ZX plane are avirtual plane parallel to the X axis direction and the Y axis direction,a virtual plane parallel to the Y axis direction and the Z axisdirection, and a virtual plane parallel to the Z axis direction and theX axis direction, respectively.

A vehicle antenna of an embodiment according to the present disclosureis suitable for transmitting and receiving electromagnetic waves inelectromagnetic frequency bands such as microwave and millimeter wavebands (for example, 0.3 GHz to 300 GHz; more particularly, 5.9 GHz). Thevehicle antenna of the embodiment according to the present disclosurecan be applied to, for example, a V2X communication system, a fifthgeneration mobile communication system (i.e., 5G), a radar system onvehicle, and the like, but the applicable systems are not limitedthereto. An example of V2X communication system includes an ETC(Electronic Toll Collection) system.

FIG. 1 is a perspective view illustrating an example of vehicleantenna-attached window glass 101 (which may be hereinafter simplyreferred to as “window glass 101”) according to the embodiment of thepresent disclosure. The window glass 101 includes a glass plate 70 aswindow of a vehicle 80 and a vehicle antenna 110 (which may behereinafter simply referred to as “antenna 110”) attached to the glassplate 70.

The glass plate 70 is, for example, a windshield provided on a frontside of the vehicle 80. The glass plate 70 is attached to a front windowframe of the vehicle 80 at a predetermined installation angle θ withrespect to the horizontal plane 90. In this example, the horizontalplane 90 is parallel to a ZX plane.

The antenna 110 is attached to the inside of the glass plate 70 with amember, not illustrated, such as a housing, and in this example, theantenna 110 is attached around the central portion of the upper sidearea of the glass plate 70. In this example, the number of antennas 110attached to one glass plate 70 is one, but two or more antennas 110 maybe attached to one glass plate 70.

FIG. 2 is a partially enlarged view illustrating, in a front view, anexample of the window glass 101. FIG. 3 is a partially enlarged viewillustrating, in a side view, an example of the window glass 101. Theantenna 110 includes a conductor plate 10, a radiator plate 20, a firstelement 51, and a second element 52.

Typically, the conductor plate 10 is a planar layer of which the surfaceis parallel to the XY plane, and functions as a ground for the antenna110. The conductor plate 10 is a plate-shaped or film-shaped conductor.Examples of materials of conductors used for the conductor plate 10include silver and copper, but the materials are not limited thereto.Although the conductor plate 10 illustrated in the drawing is square,the conductor plate 10 may have a polygonal shape other than a square,or may have another shape such as a circle. Note that the tam“plate-shaped or film-shaped” as used herein may include shapes havingthree-dimensional shapes such as, for example, convex, concave, and wavyshapes. This is also applicable to radiator plates, dielectric basematerials, first and second elements, and a single element explainedlater. However, the “plate-shaped or film-shaped” explained later ispreferably a planar shape (two-dimensional shape) because predeterminedantenna gain characteristics can be readily predicted.

The radiator plate 20 is a plate-shaped or film-shaped conductorarranged to face the conductor plate 10 in the Z axis direction. Thearea of the radiator plate 20 is smaller than the area of the conductorplate 10. The radiator plate 20 is a planar layer of which the surfaceis parallel to the XY plane, and functions as a radiating element forthe antenna 110. Examples of materials of conductors used for theradiator plate 20 include silver, copper, and the like, but thematerials are not limited thereto. Although the radiator plate 20illustrated in the drawing has a square shape, the radiator plate 20 mayhave a polygonal shape other than the square shape, or may have anothershape such as a circle.

The radiator plate 20 is spaced apart from the conductor plate 10. Themedium between the conductor plate 10 and the radiator plate 20 containsat least one of a space and a dielectric base material. FIGS. 2 and 3illustrate the case where the medium is constituted by only thedielectric base material 60. In a case where the medium is a space(air), the radiator plate 20, the conductor plate 10, the first element51, and the second element 52 (or a single element serving as any one ofthe first element 51 and the second element 52) may be fixed by ahousing, not illustrated, as necessary.

The dielectric base material 60 is a plate-shaped or film-shapeddielectric layer of which the main component is dielectric. Thedielectric base material 60 includes a first surface 61 and a secondsurface 62 on the opposite side of the first surface 61. The surfaces61, 62 are parallel to the XY plane. The surface 61, which is one of thesurfaces of the dielectric base material 60, is provided with theradiator plate 20. The surface 62, which is the other of the surfaces ofthe dielectric base material 60, is provided with the conductor plate10.

For example, the dielectric base material 60 may be a dielectricsubstrate such as a glass epoxy substrate, or may be a dielectric sheet.Examples of materials of dielectric used for the dielectric basematerial 60 include glass such as quartz glass, ceramics, fluorine resinsuch as polytetrafluoroethylene, liquid crystal polymer, cycloolefinpolymer, and the like, but the materials are not limited thereto.

FIG. 4 is a perspective view illustrating the dielectric base material60 formed with the conductor plate 10 and the radiator plate 20. FIG. 5is a cross sectional view illustrating the dielectric base material 60formed with the conductor plate 10 and the radiator plate 20. Thedielectric base material 60 includes a connection conductor 40connecting a feeding portion 30 and the radiator plate 20.

The feeding portion 30 is a portion to which electric power is suppliedwith a contact or contactless connection, and is a portion to which oneend of a feeding line, not illustrated, is connected or arranged inproximity. Specific examples of feeding lines include coaxial cables andmicrostrip lines. The other end of the feeding line is connected to acommunication device that communicates with the outside of the vehicleusing the antenna 110. The feeding portion 30 is located on a same sideas the conductor plate 10 with respect to the radiator plate 20.

The connection conductor 40 is not in contact with the conductor plate10. One end of the connection conductor 40 is connected to the feedingportion 30. The other end of the connection conductor 40 is connected,at a connection point 22, to the radiator plate 20. The connection point22 is displaced from the center of gravity 21 of the radiator plate 20.In the illustrated case, the connection point 22 is located on thenegative side in the Y axis direction with respect to the center ofgravity 21. In a case where the radiator plate 20 is a symmetric figuresuch as a square, the center of gravity 21 corresponds to the center ofthe symmetric figure.

Specific examples of the connection conductor 40 include a conductorformed in a through hole penetrating through the dielectric basematerial 60 in the Z axis direction, the center core of a coaxial cable,a conductor pin formed in a pin shape, and the like, but the connectionconductor 40 is not limited thereto. In a case where the medium betweenthe conductor plate 10 and the radiator plate includes space, specificexamples of the connection conductor 40 include the center core of acoaxial cable, a conductor pin, and the like, but the connectionconductor 40 is not limited thereto.

As illustrated in FIG. 5, in terms of improving the antenna gain of theantenna 110 in a direction from the conductor plate 10 to the radiatorplate 20, the center of gravity 21 of the radiator plate 20 preferablyoverlaps the center of gravity 11 of the conductor plate 10 as viewedfrom the same side as the radiator plate 20 with respect to theconductor plate 10. In this example, “the viewpoint on the same side asthe radiator plate 20 with respect to the conductor plate 10” representsa viewpoint on the positive side in the Z axis direction, and “thedirection from the conductor plate 10 to the radiator plate 20”represents a direction toward the positive side in the Z axis direction.

In FIG. 2, the first element 51 and the second element 52 are conductorsarranged away from each other on both sides in the vehicle-widthdirection (in the illustrated case, the X axis direction being thevehicle-width direction) with respect to the radiator plate 20. Becausethe first element 51 and the second element 52 are arranged in thismanner, the antenna gain of the antenna 110 in the vehicle-widthdirection is improved. Specifically, in a case where the first element51 and the second element 52 are not provided, the antenna gain in thetraveling direction (of the vehicle) perpendicular to the vehicle-widthdirection would be high, whereas the antenna gain in the vehicle-widthdirection would be relatively low. Therefore, the first element 51 andthe second element 52 are provided, so that the antenna gain in thetraveling direction is moderately distributed to the antenna gain in thevehicle-width direction to provide appropriate antenna gains in both ofthe traveling direction and the vehicle-width direction. In this case,where “the antenna gain in the traveling direction [dBi]-(−35 [dBi])” isdefined as A [dBi], and “the antenna gain in the vehicle-width direction[dBi]-(−35 [dBi])” is defined as B [dBi], A:B may be in a range of1:0.55 to 1:1.50, A:B is preferably in a range of 1:0.65 to 1:1.40, A:Bis more preferably in a range of 1:0.70 to 1:1.30, and A:B is still morepreferably in a range of 1:0.80 to 1:1.20. In this case, the antennagain in the vehicle-width direction is an average value of the antennagain in the direction of 90 degrees and the antenna gain in thedirection of 270 degrees in a simulation result of the antenna gain inthe azimuth directions on the ZX plane.

For example, at least one of the first element 51 and the second element52 is a planar layer of which the surface is parallel to the XY plane,and functions as a directing element or a reflecting element for theantenna 110. In this example, the first element 51 and the secondelement 52 are the same layer as each other, i.e., the surface of thefirst element 51 and the surface of the second element 52 are arrangedin parallel to the XY plane, and are located away from the center ofgravity 21 of the radiator plate 20 as viewed from the same side as theradiator plate 20 with respect to the conductor plate 10.

In this example, the size of area of each of the first element 51 andthe second element 52 is smaller than the conductor plate 10 and islarger than the radiator plate 20, but the size of area is not limitedthereto. For example, the size of area of at least one of the firstelement 51 and the second element 52 may be smaller than the radiatorplate 20, as long as a desired directivity is satisfied.

Examples of materials of conductors used for the first element 51 andthe second element 52 include silver, copper, and the like, but thematerials are not limited thereto. Also, although the first element 51and the second element 52 illustrated in the drawing have a squareshape, the first element 51 and the second element 52 may have apolygonal shape other than the square shape, or may have another shapesuch as a circle.

When at least one of the first element 51 and the second element 52 is aplate-shaped or film-shaped conductor having its normal in the Z axisdirection, the antenna gain of the antenna 110 in the positive side inthe Z axis direction is improved. In the illustrated case, both of thefirst element 51 and the second element 52 are plate-shaped orfilm-shaped conductors.

In terms of improving the antenna gain in the direction normal to thefirst element 51, the second element 52, the conductor plate 10, and theradiator plate 20 of the antenna 110, the first element 51, the secondelement 52, the conductor plate 10, and the radiator plate 20 arepreferably parallel to each other. In the illustrated case, thedirection normal to the first element 51, the second element 52, theconductor plate 10, and the radiator plate 20 is the Z axis direction,and the antenna gain toward the positive side in the Z axis direction isimproved.

For example, when, as illustrated in FIG. 2, in terms of improving theantenna gain of the antenna 110, the first element 51 and the secondelement 52 are preferably placed in a linearly symmetrical arrangementabout axis of symmetry passing through the connection point 22, wherethe connection conductor 40 is connected to the radiator plate 20 asviewed from the same side as the radiator plate 20 with respect to theconductor plate 10. In this example, the antenna gain in the X axisdirection, which is the vehicle-width direction, is improved.

FIG. 6 is a partial cross sectional view illustrating an example of anantenna system including multiple vehicle antennas. The antenna system100 as illustrated in FIG. 6 includes a windshield 71, a rear windowglass 72, a front antenna 111 attached to the windshield 71, and a rearantenna 112 attached to the rear window glass 72. Each of the windshield71 and the rear window glass 72 is an example of the glass plate 70explained above. Each of the front antenna 111 and the rear antenna 112is an example of the antenna 110 explained above. The front antenna 111is an example of a first antenna. The rear antenna 112 is an example ofa second antenna.

The radiator plate 20 of the front antenna 111 is preferably arranged atan inclination (inclination angle α) equal to or less than ±15 degreeswith respect to the vertical plane 91 perpendicular to the horizontalplane 90. Accordingly, the antenna gain in the direction parallel to thehorizontal plane 90 is improved in the front antenna 111, and becausethe first element 51 and the second element 52 are arranged away fromeach other on both sides in the vehicle-width direction, the antennagain in the vehicle-width direction is also improved. If the radiatorplate 20 of the front antenna 111 is arranged at an inclination morethan ±15 degrees with respect to the vertical plane 91 perpendicular tothe horizontal plane 90, the balance of the antenna gain in a directionparallel to the horizontal plane is lost, i.e., the difference betweenthe gain in the traveling direction of the vehicle and the gain in thevehicle-width direction may increase.

Likewise, the radiator plate 20 of the rear antenna 112 is preferablyarranged at an inclination (inclination angle α) equal to or less than±15 degrees with respect to the vertical plane 91 perpendicular to thehorizontal plane 90. Accordingly, the antenna gain in the directionparallel to the horizontal plane 90 is improved in the rear antenna 112,and because the first element 51 and the second element 52 are arrangedaway from each other on both sides in the vehicle-width direction, theantenna gain in the vehicle-width direction is improved. If the radiatorplate 20 of the rear antenna 112 is arranged at an inclination more than±15 degrees with respect to the vertical plane 91 perpendicular to thehorizontal plane 90, the balance of the antenna gain in a directionparallel to the horizontal plane is lost, i.e., the difference betweenthe gain in the traveling direction of the vehicle and the gain in thevehicle-width direction may increase.

The radiator plate 20 of the front antenna 111 is preferably arranged atan inclination equal to or less than ±10 degrees, more preferablyarranged at an inclination equal to or less than ±5 degrees, still morepreferably arranged at an inclination equal to or less than ±1 degrees,and most preferably arranged at an inclination of 0 degrees, withrespect to the vertical plane 91 perpendicular to the horizontal plane90. Likewise, the radiator plate 20 of the rear antenna 112 ispreferably arranged at an inclination equal to or less than ±10 degrees,more preferably arranged at an inclination equal to or less than ±5degrees, still more preferably arranged at an inclination equal to orless than ±1 degrees, and most preferably arranged at an inclination of0 degrees, with respect to the vertical plane 91 perpendicular to thehorizontal plane 90.

In FIG. 6, the front antenna 111 is attached to the windshield 71 sothat the radiator plate 20 is located at a vehicle-front-side withrespect to the conductor plate 10, and the rear antenna 112 is attachedto the rear window glass 72 so that the radiator plate 20 is located ata vehicle-rear-side with respect to the conductor plate 10. Therefore,the front antenna 111 improves the antenna gain in an area ranging fromthe front side of the vehicle to the vehicle-width direction, and therear antenna 112 improves the antenna gain in an area ranging from therear side of the vehicle to the vehicle-width direction. Therefore, theantenna gain in directions 360 degrees around the vehicle 80 can beimproved.

Also, the first element 51 and the second element 52 of the frontantenna 111 are preferably arranged at an inclination (inclination angleβ) equal to or less than ±15 degrees with respect to the vertical plane91 perpendicular to the horizontal plane 90. Accordingly, the antennagain in the direction parallel to the horizontal plane 90 is improved inthe front antenna 111, and because the first element 51 and the secondelement 52 are arranged away from each other on both sides in thevehicle-width direction, the antenna gain in the vehicle-width directionis improved. This is also applicable to the inclination angle β of thefirst element 51 and the second element 52 of the rear antenna 112.

Also, the conductor plate 10 of the front antenna 111 is preferablyarranged at an inclination (inclination angle γ) equal to or less than±15 degrees with respect to the vertical plane 91 perpendicular to thehorizontal plane 90. Accordingly, the antenna gain in the directionparallel to the horizontal plane 90 is improved in the front antenna111, and because the first element 51 and the second element 52 arearranged away from each other on both sides in the vehicle-widthdirection, the antenna gain in the vehicle-width direction is improved.This is also applicable to the inclination angle γ of the conductorplate 10 of the rear antenna 112.

The conductor plate 10 of the front antenna 111 is preferably arrangedat an inclination equal to or less than ±10 degrees, more preferablyarranged at an inclination equal to or less than ±5 degrees, still morepreferably arranged at an inclination equal to or less than ±1 degrees,and most preferably arranged at an inclination of 0 degrees, withrespect to the vertical plane 91 perpendicular to the horizontal plane90. Likewise, the conductor plate 10 of the rear antenna 112 ispreferably arranged at an inclination equal to or less than ±10 degrees,more preferably arranged at an inclination equal to or less than ±5degrees, still more preferably arranged at an inclination equal to orless than ±1 degrees, and most preferably arranged at an inclination of0 degrees, with respect to the vertical plane perpendicular to thehorizontal plane 90. If the conductor plate 10 of the front antenna 111is arranged at an inclination more than ±15 degrees with respect to thevertical plane 91 perpendicular to the horizontal plane 90, the balanceof the antenna gain in a direction parallel to the horizontal plane islost, i.e., the difference between the gain in the traveling directionof the vehicle and the gain in the vehicle-width direction may increase.This is also applicable to the inclination angle γ of the conductorplate 10 of the rear antenna 112.

“X is arranged at 0 degrees with respect to the vertical plane 91” meansthat X is arranged in parallel with the vertical plane 91.

In the antenna system 100 as illustrated in FIG. 6, one vehicle antennais attached to each of the windshield 71 and the rear window glass 72.However, the antenna system 100 may include: at least two window glassesfrom among the windshield 71, the rear window glass 72, and the sidewindow glass 73; and at least one vehicle antenna attached to each ofthe at least two window glasses.

FIG. 7 is a figure illustrating an example of a measurement result ofdirectivities of the vehicle antennas, and illustrates a simulationresult of antenna gains in respective azimuth directions on the ZXplane. “90 degrees” and “270 degrees” represent the vehicle-widthdirection. “0 degrees” represents the front side of the vehicle. “180degrees” represents the rear side of the vehicle. This is alsoapplicable to other graphs showing measurement results of directivities.It should be noted that this simulation result is a result obtained whenthe radiator plate, the elements, and the conductor plate of the vehicleantenna are arranged in the vertical direction perpendicular to thehorizontal plane (at an inclination of 0 degrees with respect to thevertical plane). Unless otherwise specified, other simulation resultsare also results obtained with this arrangement.

In FIG. 7, Example 1 has the configuration illustrated in FIGS. 1 to 5and 8. Comparative Example 1 has a configuration in which the firstelement 51 and the second element 52 are eliminated from theconfiguration of Example 1. In the case of Example 1, the antenna gainin the vehicle-width direction was calculated as −1.37 dBi, in theComparative Example 1, the antenna gain in the vehicle-width directionwas calculated as −9.85 dBi. Therefore, the antenna gain in thevehicle-width direction was improved in Example 1 as compared withComparative Example 1.

When the antenna gains of FIG. 7 are measured, the sizes of respectiveportions illustrated in FIGS. 1 to 6 are as follows, in units ofmillimeters.

-   -   L20: 10    -   L21: 10    -   L50: 15    -   L51: 15    -   L52: 5    -   L53: 20    -   L54: 50    -   L55: 1    -   L56: 44    -   L57: 12    -   L58: 5    -   L60: 30    -   L61: 30    -   L62: 3    -   L63: 16 (distance between the conductor plate 10 and the flange        of the vehicle 80)    -   L70: 500    -   L80: 515    -   L81: 1000    -   L82: 50

Also, the angles are as follows.

-   -   θ: 25 degrees    -   α, β, γ: 0 degrees

FIGS. 8 to 10 are drawings illustrating first to third configurationexamples of vehicle antennas, and illustrate modes in which the firstelement 51 and the second element 52 are arranged on a same side as theradiator plate 20 with respect to the conductor plate 10. FIGS. 8 to 10illustrate modes in which the first element 51 and the second element 52are arranged away from the radiator plate 20 and at least portions ofthe first element 51 and the second element 52 overlap with theconductor plate 10 as viewed from the same side as the radiator plate 20with respect to the conductor plate 10. In FIG. 8, both of the firstelement 51 and the second element 52 are arranged on an opposite side ofthe radiator plate 20 from the conductor plate 10 (i.e., the positiveside in the Z axis direction). In FIG. 9, both of the first element 51and the second element 52 are arranged in the same layer as the radiatorplate 20, i.e., the surface of the first element 51, the surface of thesecond element 52, and the surface of the radiator plate 20 are arrangedin parallel with the XY plane. In FIG. 10, both of the first element 51and the second element 52 are arranged on a same side as the conductorplate 10 with respect to the radiator plate 20 (i.e., the negative sidein the Z axis direction).

FIG. 11 is a figure illustrating an example of a measurement result ofdirectivities of the vehicle antennas, and illustrates a simulationresult of antenna gains in respective azimuth directions on the ZXplane. A case with L55=+1 mm corresponds to the configuration of FIG. 8(Example 1). A case with L55=0 mm corresponds to the configuration ofFIG. 9. Cases with L55=−1 mm and L55=−2 mm represent the configurationof FIG. 10. When the first element 51 and the second element 52 arelocated on the positive side in the Z axis direction with respect to theradiator plate 20, L55 had a positive value. When the first element 51and the second element 52 are located on the negative side in the Z axisdirection with respect to the radiator plate 20, L55 had a negativevalue. Unless otherwise specified, the sizes of the respective portionsare the same as the sizes used in the measurement of FIG. 7.

FIG. 12 illustrates the antenna gains in the vehicle-width directionwith respect to the measurement result of FIG. 11. In a case where L55was −1 mm, the antenna gain in the vehicle-width direction was improvedas compared with Comparative Example 1. In a case where L55 was 0 mm and+1 mm, the antenna gains in the vehicle-width direction were furtherimproved as compared with Comparative Example 1. In a case where L58 was+5 mm and L55 was −2 mm, the first element 51 and the second element 52were closer to the conductor plate 10 and served as a larger conductorplate than Comparative Example 1, and therefore, the antenna gain in thevehicle-width direction decreased.

FIG. 13 is a drawing illustrating a fourth configuration example of avehicle antenna, and illustrates a mode in which the first element 51and the second element 52 are separated away from each other in the Xaxis direction with respect to the third configuration example of FIG.10. FIG. 13 illustrates a mode in which the first element 51 and thesecond element 52 are arranged away from the conductor plate 10 asviewed from the same side as the radiator plate 20 with respect to theconductor plate 10.

FIG. 14 illustrates a drawing illustrating an example of a measurementresult of directivities of vehicle antennas, and illustrates asimulation result of antenna gains in respective azimuth directions onthe ZX plane. In FIG. 14, the third configuration example (FIG. 10) isarranged with L55=−2 mm and L58=+5 mm. In FIG. 14, the fourthconfiguration example (FIG. 13) is arranged with L55=−2 mm and L58=−3mm. When the first element 51 and the second element 52 overlapped theconductor plate 10 as seen from the viewpoint in the Z axis direction,L58 had a positive value. When the first element 51 and the secondelement 52 did not overlap the conductor plate 10, L58 had a negativevalue. Unless otherwise specified, the sizes of the respective portionsare the same as the sizes used in the measurement of FIG. 7.

FIG. 15 illustrates the antenna gains in the vehicle-width directionwith respect to the measurement result of FIG. 14. In the case of thefourth configuration example, the antenna gain in the vehicle-widthdirection was improved as compared with Comparative Example 1. In otherwords, when the positions of the first element 51 and the second element52 were moved to the outside in the X axis direction with respect to theconductor plate 10, the antenna gain in the vehicle-width direction wasimproved, even when L55 was −2 mm, as compared with Comparative Example1.

FIG. 16 is a drawing illustrating a fifth configuration example of avehicle antenna, and illustrates a mode in which the first element 51 isarranged on a same side as the conductor plate 10 with respect to theradiator plate 20, and the second element 52 is arranged on an oppositeside of the radiator plate 20 from the conductor plate 10. In otherwords, FIG. 16 illustrates a mode in which the first element 51 and thesecond element 52 are staggered from each other with respect to theradiator plate 20. In FIG. 16, the first element 51 is arranged at thesame position as FIG. 13 (L55=−2 mm), and the second element 52 isarranged at the same position as FIG. 8 (L55=+1 mm). The first element51 is arranged with L58=−1.5 mm, and the second element 52 is arrangedwith L58=+1.5 mm.

FIG. 17 is a drawing illustrating an example of a measurement result ofdirectivities of vehicle antennas, and illustrates a simulation resultof antenna gains in respective azimuth directions on the ZX plane.Unless otherwise specified, the sizes of the respective portions are thesame as the sizes used in the measurement of FIG. 7. Even when the firstelement 51 and the second element 52 are staggered from each other withrespect to the radiator plate 20, the antenna gain in the vehicle-widthdirection was improved. Specifically, the antenna gain in the directionof 90 degrees was 0.21 dBi, and the antenna gain in the direction of 270degrees was 2.45 dBi.

FIG. 18 is a drawing illustrating a sixth configuration example of avehicle antenna, and illustrates a mode in which both of the firstelement 51 and the second element 52 are arranged in the same layer as(i.e., coplanar with) the conductor plate 10. The first element 51 andthe second element 52 are arranged with L58=−1.5 mm. FIG. 19 is adrawing illustrating a seventh configuration example of a vehicleantenna, and illustrates a mode in which both of the first element 51and the second element 52 are arranged on an opposite side of theconductor plate 10 from the radiator plate 20. The first element 51 andthe second element 52 are arranged with L58=−1.5 mm.

FIG. 20 is a drawing illustrating an example of a measurement result ofdirectivities of vehicle antennas, and illustrates a simulation resultof antenna gains in respective azimuth directions on the ZX plane.Unless otherwise specified, the sizes of the respective portions are thesame as the sizes used in the measurement of FIG. 7. A case with L59=0mm corresponds to the configuration of FIG. 18. Cases with L59=1 mm, 4mm, 7 mm, 10 mm correspond to the configuration of FIG. 19. The distanceL59 represents a distance in the Z axis direction from the conductorplate 10 to the first element 51 and the second element 52.

FIG. 21 illustrates the antenna gains in the vehicle-width directionwith respect to the measurement result of FIG. 20. In any of the caseswhere L59 was 0 mm to 10 mm, the antenna gains in the vehicle-widthdirection were improved as compared with Comparative Example 1.

FIG. 22 is a drawing illustrating an eighth configuration example of avehicle antenna. An antenna 113 as illustrated in FIG. 22 is an exampleof a vehicle antenna. The antenna 113 includes a single element 51arranged away from the conductor plate 10 and the radiator plate 20 and,as viewed from the same side as the radiator plate 20 with respect tothe conductor plate 10, located away from the center of gravity 21 ofthe radiator plate 20. The element 51 is arranged only on the negativeside in the vehicle-width direction with respect to the radiator plate20, and as viewed from the same side as the radiator plate 20 withrespect to the conductor plate 10, arranged away from the radiator plate20. The element 51 is arranged on the same side as the radiator plate 20with respect to the conductor plate 10. The radiator plate 20, theelement 51, and the conductor plate 10 are arranged at an inclination ofequal to or less than ±15 degrees with respect to the vertical planeperpendicular to the horizontal plane.

The single element 51 may be arranged in the same layer as the radiatorplate 20 or the conductor plate 10, or may be arranged on an oppositeside of the conductor plate 10 from the radiator plate 20.

FIG. 23 is a drawing illustrating an example of a measurement result ofdirectivities of vehicle antennas of FIG. 22, and illustrates asimulation result of antenna gains in respective azimuth directions onthe ZX plan. The sizes of respective portions were as follows, in unitsof millimeters.

-   -   L50: 18    -   L51: 10    -   L58 (see FIG. 2): 1.5    -   L60: 18    -   L61: 18

Unless otherwise specified, the sizes of the other portions are the sameas the sizes used in the measurement of FIG. 7. As illustrated in FIG.23, even with the single element 51, the antenna gain in thevehicle-width direction was improved, and in particular, the antennagain was improved on the side where the element 51 was arranged (thenegative side in the X axis direction).

FIG. 24 is a drawing illustrating a ninth configuration example of avehicle antenna. The antenna 114 as illustrated in FIG. 24 is an exampleof a vehicle antenna. The antenna 114 includes a single element 52arranged away from the conductor plate 10 and the radiator plate 20 and,as viewed from the same side as the radiator plate 20 with respect tothe conductor plate 10, located away from the center of gravity 21 ofthe radiator plate 20. The element 52 is arranged only on the positiveside in the vehicle-width direction with respect to the radiator plate20, and as viewed from the same side as the radiator plate 20 withrespect to the conductor plate 10, arranged away from the radiator plate20. The element 52 is arranged on the same side as the radiator plate 20with respect to the conductor plate 10. The radiator plate 20, theelement 52, and the conductor plate 10 are arranged at an inclination ofequal to or less than ±15 degrees with respect to the vertical planeperpendicular to the horizontal plane.

The single element 52 may be arranged in the same layer as the radiatorplate 20 or the conductor plate 10, or may be arranged on an oppositeside of the conductor plate 10 from the radiator plate 20.

FIG. 25 is a drawing illustrating an example of a measurement result ofdirectivities of vehicle antennas of FIG. 24, and illustrates asimulation result of antenna gains in respective azimuth directions onthe ZX plane. The sizes of respective portions are as follows, in unitsof millimeters.

-   -   L50: 18    -   L51: 10    -   L58 (see FIG. 2): 1.5    -   L60: 18    -   L61: 18

Unless otherwise specified, the sizes of the other portions are the sameas the sizes used in the measurement of FIG. 7. As illustrated in FIG.25, even with the single element 52, the antenna gain in thevehicle-width direction was improved, and in particular, the antennagain was improved on the side where the element 52 is arranged (thepositive side in the X axis direction).

In the above simulation result, the ratio A:B was obtained as follows.In particular, in Comparative Example 1, the ratio A:B defined above was1:0.52. In contrast, with respect to the ratio A:B of the antennas otherthan Comparative Example 1 (i.e., the antenna 110 including the element51 and the element 52, and the antennas 113, 114 including the singleelement), a simulation result was obtained in which a ratio in thevehicle-width direction to the traveling direction is relatively high ascompared with Comparative Example 1, and the balance of the antennadirectivity was good.

TABLE 1 A: Traveling B: Vehicle-width Items Direction ( −35) [dBi]direction ( −35) [dBi] A:B Comparative 42.9 22.2 1:0.52 Exarnple 1 (FIG.7) Example 1 (FIG. 7) 39.5 33.6 1:0.85 L55 = + 1 mm 41.0 35.8 1:0.87(FIG. 11) L55 = 0 mm 40.2 35.8 1:0.89 (FIG. 11) L55 = − 1 mm 42.9 28.91:0.67 (FIG. 11) L55 = − 2 mm 43.3 24.6 1:0.57 (FIG. 11) ThirdConfiguration 43.3 24.6 1:0.57 Example (FIG. 14) Fourth 34.8 36.0 1:1.03Configuration Example (FIG. 14) Staggered (FIG. 17) 35.7 36.3 1:1.02 L59= 0 mm 38.5 34.5 1:0.90 (FIG. 20) L59 = 1 mm 39.2 34.0 1:0.87 (FIG. 20)L59 = 4 mm 41.6 32.1 1:0.77 (FIG. 20) L59 = 7 mm 42.7 30.4 1:0.71 (FIG.20) L59 = 10 mm 43.2 29.3 1:0.68 (FIG. 20) Antenna 113 35.4 33.3 1:0.94(FIG. 23) Antenna 114 35.4 34.5 1:0.97 (FIG. 25)

Hereinabove, the vehicle antenna, the vehicle antenna-attached windowglass, and the antenna system have been explained with reference to theembodiment, but the present invention is not limited to the aboveembodiment. Various modifications and improvements such as combinations,replacements, and the like with a part or the entirety of anotherembodiment can be made within the scope of the present invention.

For example, the present invention is not limited to the case where bothof the first element 51 and the second element 52 are arranged in thesame layer as the radiator plate 20 (see FIG. 9), and at least one ofthe first element 51 and the second element 52 may be arranged in thesame layer as the radiator plate 20.

For example, the present invention is not limited to the case where bothof the first element 51 and the second element 52 are arranged on anopposite side of the conductor plate 10 from the radiator plate 20 (seeFIG. 19), and at least one of the first element 51 and the secondelement 52 may be arranged on the side opposite the radiator plate 20.

The present invention is not limited to the case where parts of both ofthe first element 51 and the second element 52 overlap the conductorplate 10 as viewed from the same side as the radiator plate 20 withrespect to the conductor plate 10 (see FIG. 8 and the like). Forexample, a part of one of the first element 51 and the second element 52may overlap the conductor plate 10 as seen from this viewpoint.

What is claimed is:
 1. A vehicle antenna comprising: a conductor plate;a radiator plate facing the conductor plate; a feeding portion locatedon a same side as the conductor plate with respect to the radiatorplate; a connection conductor connecting the feeding portion and theradiator plate; and a first element and a second element arranged awayfrom each other on both sides in a vehicle-width direction of a vehiclewith respect to the radiator plate, wherein the radiator plate isarranged at an inclination of equal to or less than ±15 degrees withrespect to a vertical plane perpendicular to a horizontal plane, andwherein a portion of at least one of the first element and the secondelement overlaps the conductor plate, as viewed from a same side as theradiator plate with respect to the conductor plate.
 2. The vehicleantenna according to claim 1, wherein a portion of the first element anda portion of the second element overlap the conductor plate, as viewedfrom a same side as the radiator plate with respect to the conductorplate.
 3. The vehicle antenna according to claim 1, wherein the firstelement and the second element are arranged on a same side as theradiator plate with respect to the conductor plate.
 4. The vehicleantenna according to claim 3, wherein at least one of the first elementand the second element is arranged on an opposite side of the radiatorplate from the conductor plate.
 5. The vehicle antenna according toclaim 3, wherein at least one of the first element and the secondelement is arranged in a same plane as the radiator plate.
 6. Thevehicle antenna according to claim 3, wherein the first element and thesecond element are arranged in a same plane as the radiator plate. 7.The vehicle antenna according to claim 1, wherein at least one of thefirst element and the second element is arranged on an opposite side ofthe conductor plate from the radiator plate.
 8. The vehicle antennaaccording to claim 1, wherein the first element and the second elementare arranged in a same plane as each other.
 9. The vehicle antennaaccording to claim 1, wherein the first element and the second elementare located away from the radiator plate, as viewed from a same side asthe radiator plate with respect to the conductor plate.
 10. The vehicleantenna according to claim 1, wherein, as viewed from a same side as theradiator plate with respect to the conductor plate, the first elementand the second element are linearly symmetrical about an axis ofsymmetry passing through a connection point where the connectionconductor is connected to the radiator plate.
 11. The vehicle antennaaccording to claim 1, wherein the first element and the second elementare arranged at an inclination of equal to or less than ±15 degrees withrespect to the vertical plane perpendicular to the horizontal plane. 12.The vehicle antenna according to claim 1, wherein the first element andthe second element have a polygonal shape other than a square shape. 13.The vehicle antenna according to claim 1, wherein the vehicle antenna isapplicable to Vehicle-to-Everything, V2X, communication.
 14. A vehicleantenna-attached window glass comprising: a glass plate for a window ofa vehicle; and at least one vehicle antenna according to claim 1attached to the glass plate.
 15. A vehicle antenna comprising: aconductor plate; a radiator plate facing the conductor plate; a feedingportion located on a same side as the conductor plate with respect tothe radiator plate; a connection conductor connecting the feedingportion and the radiator plate; and a single element arranged away fromthe conductor plate and the radiator plate, and located away from acenter of gravity of the radiator plate, as viewed from a same side asthe radiator plate with respect to the conductor plate, wherein theradiator plate is arranged at an inclination of equal to or less than±15 degrees with respect to a vertical plane perpendicular to ahorizontal plane.
 16. The vehicle antenna according to claim 15, whereinthe single element is arranged on one side in a vehicle-width directionwith respect to the radiator plate.
 17. The vehicle antenna according toclaim 15, wherein the single element is arranged on a same side as theradiator plate with respect to the conductor plate.
 18. The vehicleantenna according to claim 15, wherein at least a portion of the singleelement overlaps the conductor plate, as viewed from a same side as theradiator plate with respect to the conductor plate.
 19. The vehicleantenna according to claim 15, wherein the single element is arranged ina same plane as the radiator plate.
 20. The vehicle antenna according toclaim 15, wherein the single element does not overlap with the conductorplate, as viewed from a same side as the radiator plate with respect tothe conductor plate.